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Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?

On 10/22/2010 10:34 AM, owens@netptc.net wrote:

---- Original Message ----
From: ron.l.johnson@cox.net
To: debian-user@lists.debian.org
Subject: Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?
Date: Fri, 22 Oct 2010 02:00:45 -0500

Correct.  The amount of effort needed for cross-CPU communication,
cache coherency and OS process coordination increases much more than

linearly as you add CPUs.

In fact IIRC the additional overhead follows the square of the number
of CPUs.

Maybe in brute-force implementations, but otherwise the machine would bog down after just a few CPUs.

Note that h/w engineers and OS designers/writers have put a lot of work into minimizing the overhead and maximize the parallelism of extra CPUs.

Seek truth from facts.

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